Head-to-head economic evaluations of the SGAMs are still rare, they are often based on research designs that are methodologically weak [186], and their findings do not point consistently in any one direction.

Only one cost-effectiveness study using a RCT design has been published. On the basis of an analysis of data for the 150 US patients included in a larger, multi-country RCT, Edgell et al. [193] concluded that medication and in-patient costs were lower for patients treated with olanzapine than for those treated with risperidone, though total costs did not differ significantly. Superior outcomes led these authors to conclude that olanzapine was the more cost-effective treatment for this group of patients.

A recently completed European study which used an RCT design to collect data prospectively over 6months found amisulpride and risperidone to be equallycost-effective [194]. Interestingly, there were differences between Eastern and Western European sites in terms of service-use pattern, relative costs, and the balance between costs and outcomes, reinforcing the view that economic evidence does not always ‘travel’ well across countries and health systems.

Economic studies with naturalistic designs have, to date, focused on the comparison between olanzapine and risperidone. These studies collected data either prospectively or retrospectively, and some used quite narrow measures of cost. Some of the studies point to relative advantages for risperidone [195,196] and some to relative advantages for olanzapine [197]. Calculating costs across a wide range of services, Lewis et al. [198] found no significant cost differences for patients on risperidone, olanzapine and clozapine. Methodological limitations – some of which were quite substantial (such as a narrow focus solely on drug costs) – and the draft status of some of these papers, however, make it impossible to reach overall conclusions about the comparative cost-effectiveness of the various SGAMs.

Incentives

The economic evidence on the SGAMs points to cost-effectiveness advantages over conventional medications, and the possibility (as yet unproven) of some cost-effectiveness differences between the newer drugs. However, none of the cost advantages shown for the newer drugs with respect to the old medication has been particularly large, and none is likely to accrue immediately because a large part of the savings will come from the reduced need for hospitalization. More-over, there are disincentives inherent in most health systems because the higher acquisition costs (prices) of the SGAMs are often carried by one budget (pharmacy) while the downstream savings fall elsewhere. Contractual and managerial steps may need to be taken to ensure that narrow budgetary concerns do not compromise the pursuit of overall cost-effectiveness improvements [199].